Image processing apparatus, image processing method, and program

ABSTRACT

An image processing apparatus includes a control unit configured to control execution of monochromatic calibration and multi-color calibration, and a registration unit configured to register paper types of paper to be used at time of execution of the monochromatic calibration, a monochromatic target value set for each of the paper types used for the monochromatic calibration, paper types of paper to be used at time of execution of multi-color calibration, and a multi-color target value set for each of the paper types used for the multi-color calibration. The image processing apparatus executes the multi-color calibration, after executing the monochromatic calibration, via the control unit by using paper of a paper type selected from common paper types out of the registered paper types and the monochromatic target value and the multi-color target value set for the selected paper type.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. patent applicationSer. No. 15/002,196 filed Jan. 20, 2016, which is a Continuation of U.S.patent application Ser. No. 14/091,905 filed Nov. 27, 2013, now U.S.Pat. No. 9,300,816, which claims the benefit of priority from JapanesePatent Application No. 2012-261308 filed Nov. 29, 2012, each of which ishereby incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to an image processing apparatus forcorrecting the color of an image output from a printer, an imageprocessing method therefor, and a program for generating imageprocessing parameters.

Description of the Related Art

With the improved performance of electrophotographic apparatuses inrecent years, some electrophotographic apparatuses have achieved animage quality equivalent to that of a printing machine. However, thereremains a problem that such electrophotographic apparatuses have alarger color variation amount than that of a printing machine because ofthe instability specific to the electrophotographic process. Therefore,conventional electrophotographic apparatuses employ various calibrationtechniques.

To correct primary colors, a conventional electrophotographic apparatusemploys a calibration technique for generating a look up table (LUT) forcorrecting one-dimensional (1D) gradation corresponding to the cyan,magenta, yellow, and black toners. The LUT refers to a table indicatingoutput data corresponding to input data delimited at specific intervals.The LUT enables expressing nonlinear characteristics that cannot berepresented by arithmetic formulas. A color produced by using each ofthe C, M, Y, and K toners is referred to as “monochromatic color”.Performing “monochromatic” calibration enables correcting themonochromatic color reproduction characteristics, such as a maximumdensity and a gradation.

In recent years, Japanese Patent Application Laid-Open No. 2011-254350discusses a technique for performing “multi-color” calibration by usinga four-dimensional (4D) LUT. “Multi-color” means a color produced by aplurality of color toners. For example, the red, green, and blue colorsare produced by using two out of the C, M, and Y colors. The gray coloris produced by using the C, M, and Y colors. Particularly withelectrophotography, expressing “multi-color” by using a plurality ofcolor toners often produces a nonlinear difference even if themonochromatic gradation characteristics are corrected by using aone-dimensional LUT. In this case, executing multi-color calibrationenables correcting the color reproduction characteristics of amulti-color expressed in combination (superposition) of a plurality ofcolor toners.

The following describes a flow of calibration including “multi-color”calibration. First of all, to execute “monochromatic” calibration, apatch image is printed on a recording medium, such as paper, by usingmonochromatic chart data. This patch image having a single density and apredetermined area is used for measurement. When a plurality of patchimages having different colors is generated and printed on a recordingmedium, these path images are collectively referred to as a patternimage. The recording medium, such as paper, on which the pattern imageis printed is read by using a scanner or a sensor to read the patchimages. Data obtained by reading the patch images is compared with apreset target value to generate a one-dimensional (1D) LUT forcorrecting the difference from the target value. Then, to execute“multi-color” calibration, patch images are printed on a recordingmedium by using multi-color chart data reflecting the 1D LUT generatedpreviously, and then the patch images are read by using a scanner or asensor. Data obtained by reading the patch images is compared with apreset target value to generate a four-dimensional (4D) LUT forcorrecting the difference from the target value.

As described above, high-precision correction is feasible by correctingthrough “multi-color” calibration the multi-color characteristics whichcannot be corrected only through “monochromatic” calibration.

A result of calibration is affected if the density and color of tonerapplied to paper is change by the type of the sheet (paper type).Therefore, it is important to associate the paper type with the targetvalue preset for each paper type. Japanese Patent Application Laid-OpenNo. 2007-272112 discusses a technique for selecting paper at the time ofexecution of each calibration, selecting internal parameters suitablefor the selected sheet, and executing calibration.

With the conventional technique, paper to be used is separatelyoptimized at the time of execution of each calibration. When a pluralityof calibrations for different correction targets is executed, such asmonochromatic calibration and multi-color calibration, it is necessaryto select paper types to be used before execution of each calibration,or to select a sheet feed stage storing paper belonging to the selectedpaper type. The user needs to make setting in this way before executionof each calibration. As a result, workloads on user operations increasecausing a problem that user's intervention cannot be reduced incalibration processing.

Although the target value used for correction in monochromaticcalibration differs for each paper type, calibration may be performed,in some cases, so that the density ratio in halftone and maximum densityvalue becomes constant for each paper type. In this case, since theapplied toner amount corresponding to an output signal differs for eachpaper type, the applied toner amount required to output a certain colorimage differs for each paper type.

Specifically, after execution of monochromatic calibration by usingdifferent paper, a different color is output since a correction tablediffers for each paper type.

Under this condition, a target value for multi-color calibration isregistered. To register a target value at the time of execution ofmulti-color calibration, a toner image actually printed on paper ismeasured, and the result of the measurement is registered as a targetvalue.

Since this target value for multi-color calibration is registered afterexecution of monochromatic calibration, the target value differs foreach type of paper which has been used at the time of execution ofmonochromatic calibration.

For example, when an image processing apparatus supporting paper types Aand B performs monochromatic calibration by using paper of the papertype A, the apparatus outputs an image by using a correction table A.

In multi-color calibration executed in this case, the apparatus uses aselected one of two different target values (a target value A1registered by using paper of the paper type A and a target value B1registered by using paper of the paper type B).

On the other hand, when the same image processing apparatus performsmonochromatic calibration by using paper of the paper type B, theapparatus outputs an image by using a correction table B which isdifferent from the correction table A. Therefore, since color correctionis performed by using a different correction table from the onepreviously used, the apparatus also needs to change the target value.

Therefore, in multi-color calibration executed in this case, theapparatus uses a selected one of two different target values (a targetvalue A2 registered by using paper of the paper type A and a targetvalue B2registered by using paper of the paper type B).

Specifically, a plurality of target values for multi-color calibrationsis required for each paper type of paper that has been used formonochromatic calibration.

As described above, if two different paper types are usable at the timeof execution of monochromatic calibration and at the time of executionof multi-color calibration, there are two different target values forthe paper types for multi-color calibrations corresponding to each ofthe two different types of paper for monochromatic calibration.Specifically, a total of four different target values are required formulti-color calibration.

Registering a plurality of target values for multi-color calibrationsfor each paper type used at the time of execution of monochromaticcalibration takes time and effort in this way, resulting in complicatedprocessing.

Therefore, it is desired to conform a paper type of paper to be used atthe time of execution of monochromatic calibration to a paper type ofpaper to be used at the time of execution of multi-color calibration.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, an image processingapparatus includes an image forming unit configured to form an image, acolorimetry unit configured to perform colorimetry on the image formedby the image forming unit, a control unit configured to controlexecution of monochromatic calibration in which the colorimetry unitperforms colorimetry on a monochromatic image formed on paper by theimage forming unit by using a monochromatic recording agent, and theimage forming unit corrects reproduction characteristics of amonochromatic image formed on paper of the same paper type as the paperhaving the monochromatic image formed thereon, based on a result of thecolorimetry and a monochromatic target value set for the paper type ofthe paper having the monochromatic image formed thereon, and to controlexecution of multi-color calibration in which the colorimetry unitperforms colorimetry on a multi-color image formed on paper by the imageforming unit by using a plurality of color recording agents, and theimage forming unit corrects reproduction characteristics of amulti-color image formed on paper of the same paper type as the paperhaving the multi-color image formed thereon, based on a result of thecolorimetry and a multi-color target value set for the paper type of thepaper having the multi-color image formed thereon, a registration unitconfigured to register paper types of paper on which a monochromaticimage is to be formed by execution of the monochromatic calibration, amonochromatic target value set for each of the paper types used for themonochromatic calibration, paper types of paper on which a multi-colorimage is to be formed by execution of the multi-color calibration, and amulti-color target value set for each of the paper types used for themulti-color calibration, and a selection unit configured to select apaper type out of paper types common to the paper types of paper onwhich a monochromatic image is to be formed by execution of themonochromatic calibration registered by the registration unit and to thepaper types of paper on which a multi-color image is to be formed byexecution of the multi-color calibration registered by the registrationunit. The image processing apparatus executes the multi-colorcalibration, after executing the monochromatic calibration, via thecontrol unit by using paper belonging to the paper type selected by theselection unit and the monochromatic target value and the multi-colortarget value set for the selected paper type.

According to exemplary embodiments of the present invention, in the caseof continuous execution of a plurality of calibrations for differentcorrection targets, it becomes easier to conform a paper type of paperto be used at the time of execution of monochromatic calibration to apaper type of paper to be used at the time of execution of multi-colorcalibration. This eliminates the need of registering a plurality oftarget values for multi-color calibration.

According to exemplary embodiments of the present invention, it becomespossible to select through one piece of processing a sheet feed stagestoring a paper type or paper belonging to the relevant paper type.Specifically, one paper type to be used at the time of execution of aplurality of calibrations can be selected through single paperselection.

Accordingly, in the case of continuous execution of a plurality ofcalibrations for different correction targets, a calibration executioninstruction can be received from the user with reduced processing.

Thus, user's workloads can be reduced to reduce user's intervention wheninstructing calibration execution.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a configuration of a multifunction peripheral (MFP)according to an exemplary embodiment.

FIG. 2 illustrates a configuration of an image processing unit accordingto an exemplary embodiment.

FIG. 3 is a flowchart illustrating operations in monochromaticcalibration.

FIG. 4 is a flowchart illustrating operations in multi-colorcalibration.

FIGS. 5A, 5B, and 5C illustrate examples of chart data.

FIG. 6 illustrates an example of sheet feed stages of the MFP.

FIG. 7 illustrates a monochromatic calibration execution instructionscreen.

FIG. 8 illustrates a paper registration screen for monochromaticcalibration.

FIG. 9 illustrates a paper selection screen for monochromaticcalibration.

FIG. 10 illustrates a multi-color calibration execution instructionscreen.

FIG. 11 illustrates a paper registration screen for multi-colorcalibration.

FIG. 12 illustrates a paper selection screen for multi-colorcalibration.

FIG. 13 illustrates a portal screen for various operations.

FIG. 14 is a flowchart illustrating operations of a first exemplaryembodiment.

FIG. 15 illustrates an example of paper types registered for eachcalibration.

FIG. 16 illustrates an example of a sheet feed stage selection screenaccording to the first exemplary embodiment.

FIG. 17 illustrates another example of a sheet feed stage selectionscreen according to the first exemplary embodiment.

FIG. 18 is a flowchart illustrating operations according to a secondexemplary embodiment.

FIG. 19 illustrates an example of a sheet feed stage selection screenaccording to the second exemplary embodiment.

FIG. 20 illustrates an example of a sheet feed stage selection screenaccording to a third exemplary embodiment.

DESCRIPTION OF THE EMBODIMENTS

Various exemplary embodiments, features, and aspects of the inventionwill be described in detail below with reference to the drawings.

FIG. 1 is a block diagram illustrating a system according to anexemplary embodiment. A multifunction peripheral (MFP) 101, which is acolor image processing apparatus using cyan, magenta, yellow, and black(C, M, Y, and K) toners, is connected with other network-basedapparatuses via a network 123. A personal computer (PC) 124 is connectedwith the MFP 101 via the network 123. A printer driver 125 in the PC 124transmits print data to the MFP 101.

The MFP 101 will be described in detail below. A network interface (I/F)122 receives print data. A controller 102 includes a central processingunit (CPU) 103, a renderer 112, and an image processing unit 114. Aninterpreter 104 of the CPU 103 interprets a page description language(PDL) portion of the received print data to generate intermediatelanguage data 105.

A color management system (CMS) 106 performs color conversion by using asource profile 107 and a destination profile 108 to generateintermediate language data (after CMS) 111. The CMS 106 performs colorconversion by using profile information (described below). The sourceprofile 107 is a profile for converting a device-dependent color space,such as RGB and CMYK, into a device-independent color space, such asL*a*b* (hereinafter referred to as Lab) prescribed by the InternationalCommission on Illumination (CIE) or XYZ. XYZ, a device-independent colorspace similar to Lab, represents color with three different stimulusvalues. The destination profile 108 is a profile for converting adevice-independent color space into the CMYK color space dependent on adevice (a printer 115).

On the other hand, a CMS 109 performs color conversion by using a devicelink profile 110 to generate intermediate language data (after CMS) 111.The device link profile 110 is a profile for directly converting adevice-dependent color space, such as RGB and CMYK, into the CMYK colorspace dependent on a device (the printer 115). Which of the CMS 106 andthe CMS 109 is selected depends on a setting in the printer driver 125.

Although, in the present exemplary embodiment, a plurality of CMS's (theCMS's 106 and 109) are used for a plurality of types of profiles (theprofiles 107, 108, and 110), the configuration is not limited thereto. Aplurality of types of profiles may be handled by one CMS. Further, typesof profiles are not limited to those in the present exemplaryembodiment. Any types of profiles may be used as long as the CMYK colorspace dependent on a device (the printer 115) is used.

The renderer 112 generates a raster image 113 based on the generatedintermediate language data (after CMS) 111. The image processing unit114 executes image processing on the raster image 113 and an image readby a scanner 119. The image processing unit 114 will be described indetail below.

The printer 115 connected with the controller 102 forms on paper a colorimage based on output data by using the C, M, Y, and K color toners. Theprinter 115 includes a sheet feeding unit 116 for feeding a sheet, asheet discharge unit 117 for discharging a sheet having an image formedthereon, and a measurement unit 126.

The measurement unit 126 includes a sensor 127 (a colorimetry portion)capable of acquiring the spectral reflectance and values of adevice-independent color space, such as Lab and XYZ, and is controlledby the CPU 129, which controls the printer 115. The measurement unit 126measures a patch image printed on a recording medium, such as paper, bythe printer 115.

The measurement unit 126 may be a sensor (hereinafter referred to as apost-fixing sensor) for measuring the patch image which has been fixedon paper. The measurement unit 126 is disposed on a sheet conveyancepath between sheet fixing and sheet discharge in the printer 115, andreads an output chart image. Therefore, the use of the sensor 127disposed in the printer 115 enables reading a chart image without user'sintervention during measurement.

The patch image having a single density and a predetermined area is usedfor measurement. When a plurality of patch images having differentcolors is generated, and the generated patch images are printed on arecording medium, the path images are collectively referred to as apattern image. The sensor 127 included in the measurement unit 126 readsthe pattern image, and transmits read numerical information to thecontroller 102. The controller 102 executes calculation by usingrelevant numerical information, and utilizes the result of thecalculation at the time of execution of monochromatic calibration andmulti-color calibration.

A display unit 118 is a user interface (UI) for displaying aninstruction to a user and the status of the MFP 101. The display unit118 is utilized at the time of execution of monochromatic calibrationand multi-color calibration (described below).

The scanner 119 includes an automatic document feeder. The scanner 119irradiates an image on a bundle of document sheets or a one documentsheet with light from a light source (not illustrated), and focuses animage reflected by a document sheet on a solid-state image sensor, sucha charge-coupled device (CCD) sensor, through a lens. Then, the scanner119 obtains a raster-form image read signal as image data from thesolid-state image sensor.

An input unit 120 is an interface for receiving an input from the user.A part of the input unit 120 may be a touch panel, and integrated withthe display unit 118.

A storage device 121 stores data processed by the controller 102 anddata received by the controller 102.

A measuring unit 128 is an external measurement unit connected to thenetwork 123 or the PC 124. Similar to the measurement unit 126, themeasuring unit 128 is able to acquire the spectral reflectance andvalues of a device-independent color space, such as Lab and XYZ.

Processing executed by the image processing unit 114 will be describedbelow. FIG. 2 is a flowchart illustrating image processing to beperformed on the raster image 113 and an image read by the scanner 119.The processing of the flowchart illustrated in FIG. 2 is implementedwhen an application-specific integrated circuit (ASIC) (not illustrated)in the image processing unit 114 executes each step.

In step S201, the image processing unit 114 receives image data. Theimage processing unit 114 determines whether the received data is scandata received from the scanner 119 or the raster image 113 sent from theprinter driver 125.

When the received data is determined not to be scan data (NO in stepS202), then in step S211, the received data is the raster image 113rasterized in bitmap form by the renderer 112, and the CMS converts thereceived data into a CMYK image 211 dependent on a printer device.

When the received data is determined to be scan data, i.e., an RGB image203 (YES in step S202), then in step S204, the image processing unit 114executes color conversion processing to generate a common RGB image 205.The common RGB image 205 is defined in the device-independent RGB colorspace, and can be converted into a device-independent color space, suchas Lab, through calculation.

In step S206, on the other hand, the image processing unit 114 executescharacter determination processing to generate character determinationdata 207 by detecting, in this case, edges of the image.

In step S208, the image processing unit 114 executes filter processingon the common RGB image 205 by using the character determination data207. The image processing unit 114 executes different filter processingon the character portion and on other portions, by using the characterdetermination data 207.

In step S209, the image processing unit 114 executes background colorremoval processing. In step S210, the image processing unit 114 executescolor conversion processing to generate the CMYK image 211.

In step S212, the image processing unit 114 executes multi-colorcorrection processing by using a 4D-LUT 217. A 4D-LUT refers to afour-dimensional look up table (LUT) for converting a combination ofsignal values when outputting the C, M, Y, and K toners into acombination of C, M, Y, and K signal values. The 4D-LUT 217 is generatedby “multi-color calibration” (described below). The use of the 4D-LUTenables correcting “multi-color” using a plurality of toners.

After completion of the multi-color correction processing in step S212,in step S213, the image processing unit 114 corrects the gradationcharacteristics for each of the C, M, Y, and K monochromatic colors byusing a 1D-LUT 218. A 1D-LUT refers to a one-dimensional look up table(LUT) for correcting each of the C, M, Y, and K monochromatic colors.The 1D-LUT 218 is generated by “monochromatic calibration” describedbelow.

In step S214, the image processing unit 114 executes halftoneprocessing, such as screen processing and error diffusion processing, togenerate a CMYK image (binary) 215. In step S216, the image processingunit 114 transmits the image data to the printer 115.

The following describes “monochromatic calibration” for correcting themonochromatic gradation characteristics output from the printer 115,with reference to FIG. 3. Performing monochromatic calibration enablescorrecting the monochromatic color reproduction characteristics, such asthe maximum density characteristics and the gradation characteristics.The color reproduction characteristics corresponding to each of the C,M, Y, and K toners used in the printer 115 are corrected together at thetime of execution of calibration. Specifically, the processingillustrated in FIG. 3 is executed at the same time for each of the C, M,Y, and K colors.

FIG. 3 is a flowchart illustrating processing for generating the 1D-LUT218 for correcting the monochromatic gradation characteristics. Theprocessing of the flowchart illustrated in FIG. 3 is implemented whenthe CPU 103 executes each step. The generated 1D-LUT 218 is stored inthe storage device 121. The CPU 103 displays an instruction for the useron a UI via the display unit 118, and receives a user instruction fromthe input unit 120.

In step S301, the CPU 103 acquires chart data (A) 302 stored in thestorage device 121. The chart data (A) 302, used for correcting themaximum density for each of the C, M. Y, and K monochromatic colors,includes such a signal value (for example, 255) that gives maximumdensity data for each of the C, M, Y, and K monochromatic colors.

In step S303, the CPU 103 executes image processing on the chart data(A) 302 via the image processing unit 114, and prints a chart image (A)304 (pattern image) at the printer 115. Examples are illustrated inFIGS. 5A, 5B, and 5C. FIG. 5A illustrates an example of a pattern image501 produced by printing the chart data (A) 302. Patch images 502, 503,504, and 505 are printed with the maximum density of the C, M, Y, and Kmonochromatic colors, respectively. Thus, the chart image (A) 304(pattern image) includes a plurality of patch images. In this case, theimage processing unit 114 executes only halftone processing in stepS214, and executes neither the correction processing with the 1D-DUT instep S213 nor the correction processing with the 4D-DUT in step S212.

In step S305, the CPU 103 executes density measurement of a printproduct of the chart image (A) 304 by using the scanner 119 and thesensor 127 in the measurement unit 126 to obtain a measurement value (A)306.

When executing calibration without user's intervention, the CPU 103measures the chart image (A) 304 by using the sensor 127. Themeasurement value (A) 306 is a density value for each of the C, M, Y,and K colors. In step S307, the CPU 103 corrects the maximum density ofthe measurement value (A) 306 for each color by using the measurementvalue (A) 306 and a preset target value (A) 308 of the maximum densityvalue. The CPU 103 adjusts device setting values of the printer 115,such as a laser output and a developing bias, so that the maximumdensity approaches the target value 308 (A).

In step S309, the CPU 103 acquires chart data (B) 310 stored in thestorage device 121. The chart data (B) 310 includes signal values forgradation data of the C, M, Y, and K “monochromatic colors”. FIG. 5Billustrates an example of a chart image (B) 312 (pattern image) having aplurality of patch images printed on a recording medium based on thechart data (B) 310. FIG. 5B illustrates an example of a print product ofthe chart image (B) 312 having the plurality of patch images printed ona recording medium based on the chart data (B) 310. Referring to FIG.5B, patch images 507, 508, 509, and 510, and the subsequent patch imagesto the right thereof include gradation data of the C, M, Y, and Kcolors, respectively. Thus, the chart image (B) 312 (pattern image)includes a plurality of patch images.

In step S311, the CPU 103 executes image processing on the chart data(B) 310 via the image processing unit 114, and prints the chart image(B) 312 at the printer 115. In this case, the image processing unit 114executes only halftone processing in step S214, and executes neither thecorrection processing with the 1D-DUT in step S213 nor the correctionprocessing with the 4D-DUT in step S212. Since the printer 115 correctsthe maximum density in step S307 as described above, the maximum densityis equivalent to the target value (A) 308.

In step S313, the CPU 103 executes measurement by using the scanner 119and the sensor 127 to obtain a measurement value (B) 314.

To execute calibration without user's intervention, the CPU 103 measuresthe chart image (B) 314 by using the sensor 127.

The measurement value (B) 314 is a density value acquired from thegradation for each of the C, M, Y, and K colors. In step S315, the CPU103 generates a 1D-LUT 218 for correcting the monochromatic gradation byusing the measurement value (B) 314 and a preset target value (B) 316.

The following describes “multi-color calibration” for correcting themulti-color characteristics output from the printer 115, with referenceto FIG. 4. Performing multi-color calibration enables correcting themulti-color reproduction characteristics expressed by a combination (forexample, superposition) of a plurality of color toners. The processingof the flowchart illustrated in FIG. 4 is implemented when the CPU 103in the controller 102 executes each step. This acquired 4D-LUT 217 isstored in the storage device 121. The CPU 103 displays an instructionfor the user on a UI via the display unit 118, and receives a userinstruction from the input unit 120.

In multi-color calibration, the CPU 103 corrects multi-color output fromthe printer 115 after execution of monochromatic calibration. Therefore,it is desirable to execute multi-color calibration immediately afterexecution of monochromatic calibration.

In step S401, the CPU 103 acquires information of “multi-color” chartdata (C) 402 stored in the storage device 121. The chart data (C) 402,used for multi-color correction, includes “multi-color” signal valueswhich are a combination of the C, M, Y, and K colors. FIG. 5Cillustrates an example of a chart image (C) 404 (pattern image) having aplurality of patch images printed on a recording medium based on thechart data (C) 402. FIG. 5C illustrates a pattern image 511 produced byprinting the chart data (C) 402. A patch image 512 and all other patchimages printed on the pattern image 511 are formed of a multi-color,i.e., a combination of the C, M, Y, and K toners. Thus, the chart image(C) 404 (pattern image) includes a plurality of patch images.

In step S403, the CPU 103 executes image processing on the chart data(C) 402 via the image processing unit 114, and prints the chart image(C) 404 at the printer 115. In multi-color calibration, to correct thedevice multi-color characteristics after execution of monochromaticcalibration, the 1D-LUT 218 generated at the time of execution ofmonochromatic calibration is used for image processing by the imageprocessing unit 114.

In step S405, the CPU 103 executes multi-color measurement of the printproduct of the chart image (C) 404 by using the scanner 119 and thesensor 127 in the measurement unit 126 to acquire a measurement value(C) 406.

To execute calibration without user's intervention, the CPU 103 measuresthe chart image (C) 406 by using the sensor 127.

The measurement value (C) 406 indicates the multi-color characteristicsof the printer 115 after execution of monochromatic calibration.Further, the measurement value (C) 406 is a value in adevice-independent color space, and is referred to as Lab in the presentexemplary embodiment. When the scanner 119 is used, the CPU 103 convertsan RGB value into an Lab value based on a 3D-LUT (not illustrated).

In step S407, the CPU 103 acquires an Lab-to-CMY 3D-LUT 409 stored inthe storage device 121, reflects the difference between the measurementvalue 406 (C) and a preset target value (C) 408 to the Lab-to-CMY 3D-LUT409, and generates an Lab-to-CMY 3D-LUT (after correction) 410. AnLab-to-CMY 3D-LUT is a 3D LUT for outputting a CMY value correspondingto an input Lab value.

A method for generating an Lab-to-CMY 3D-LUT will be described below.The CPU 103 adds a difference between the measurement value 406 (C) andthe preset target value (C) 408 to the Lab value on the input side ofthe Lab-to-CMY 3D-LUT 409, and executes interpolating calculation basedon the Lab-to-CMY 3D-LUT 409 on the Lab value to which the difference isreflected. As a result, the CPU 103 generates an Lab-to-CMY 3D-LUT(after correction) 410.

In step S411, the CPU 103 acquires a CMY-to-Lab 3D-LUT 412 stored in thestorage device 121, and executes calculation based on the Lab-to-CMY3D-LUT (after correction) 410. Thus, the CPU 103 generates theCMYK-to-CMYK 4D-LUT 217. A CMY-to-Lab 3D-LUT of is a 3D LUT foroutputting an Lab value corresponding to an input CMY value.

A method for generating the CMYK-to-CMYK 4D-LUT 217 is illustratedbelow. The CPU 103 generates a CMY-to-CMY 3D-LUT based on the CMY-to-Lab3D-LUT 412 and the Lab-to-CMY 3D-LUT (after correction) 410. Then, theCPU 103 generates the CMYK-to-CMYK 4D-LUT 217 so that the input valueand the output value of K coincide with each other. A CMY-to-CMY 3D-LUTis a 3D LUT for outputting a CMY value after correction corresponding toan input CMY value.

FIG. 13 illustrates an example of a portal screen displayed whenmonochromatic calibration and multi-color calibration are selectivelyexecuted.

This portal screen collects buttons for various calibrations and otherfunctions frequently used, and includes at least a CONTINUOUSCALIBRATION button 1304 for continuously executing monochromaticcalibration and multi-color calibration. The screen may further includea MONOCHROMATIC CALIBRATION button 1302 for performing monochromaticcalibration, a MULTI-COLOR CALIBRATION button 1303 for performingmulti-color calibration, and other buttons.

When the MONOCHROMATIC CALIBRATION button 1302 is pressed, the screenchanges to a MONOCHROMATIC CALIBRATION execution instruction screen 701.

When the MULTI-COLOR CALIBRATION button 1303 is pressed, the screenchanges to a MULTI-COLOR CALIBRATION execution instruction screen 1001.

When the CONTINUOUS CALIBRATION button 1304 is selected, a screen forsheet feed stage selection illustrated in FIG. 16 is displayed, andcontinuous calibration is executed by using paper belonging to theselected paper type. FIG. 16 will be described below.

Specifically, after completion of monochromatic calibration, the CPU 103prints the chart image (C) 404 for multi-color calibration, and startsmulti-color calibration. Alternatively, the CPU 103 may display a buttonfor starting multi-color calibration on a UI screen, and startmulti-color calibration when the button is pressed by the user.

On the other hand, when the MONOCHROMATIC CALIBRATION button 1302 isselected, the CPU 103 executes only monochromatic calibration.Similarly, when the MULTI-COLOR CALIBRATION button 1303 is pressed, theCPU 103 executes only multi-color calibration.

The following describes the reason why different buttons are used formonochromatic calibration and multi-color calibration. When printing thechart image (C) 404 used at the time of execution of multi-colorcalibration, the CPU 103 uses the 1D-LUT 218 generated in monochromaticcalibration. Therefore, it is desirable to correct the multi-colorreproduction characteristics by performing multi-color calibrationimmediately after monochromatic calibration, i.e., immediately after themonochromatic color reproduction characteristics have been corrected.However, if two different calibrations are performed, the user willconsume much processing time for calibrations.

Therefore, to reduce processing time, the CPU 103 executes eithermulti-color calibration or monochromatic calibration depending on theuser's operating environment. Thus, there arises a difference betweenfrequencies of execution of the two calibrations. For example, a userwho frequently performs monochromatic printing performs multi-colorcalibration not so frequently. Further, a user who frequently performsmulti-color printing, such as photograph printing, frequently performsmulti-color calibration.

The CPU 103 may control the timing at which a color correction menu canbe selected.

In many cases, the power of an image processing apparatus is turned offduring the night and turned on in the morning. Therefore, when a mainpower switch of the MFP 101 is turned ON and the power is supplied, theCPU 103 may enable only the CONTINUOUS CALIBRATION button 1304.Alternatively, when neither of the two calibrations is performed withina predetermined time duration, the CPU 103 may enable only theCONTINUOUS CALIBRATION button 1304. Alternatively, when neither of thetwo calibrations is performed until printing is made for a predeterminednumber of sheets, the CPU 103 may enable only the CONTINUOUS CALIBRATIONbutton 1304.

Alternatively, when a predetermined time duration has elapsed, whenprinting is made on a predetermined number of sheets, or when the poweris turned ON, monochromatic calibration and multi-color calibration maybe automatically performed in succession in this order.

When the user performs calibration at a predetermined timing, the CPU103 allows the user to select only the CONTINUOUS CALIBRATION button1304 as described above, thus prompting the user to execute multi-colorcalibration immediately after execution of monochromatic calibration atpredetermined intervals.

Therefore, the user is allowed to select either execution of bothcalibrations (monochromatic calibration and multi-color calibration inthis order as described above) or execution of either monochromaticcalibration or multi-color calibration. Thus, the user is allowed tosuitably perform calibration according to user's operating conditions.

Performing control to allow the user to select only execution of bothcalibrations at predetermined intervals enables preventing reduction inreproduction characteristics correction accuracy due to execution ofeither one calibration. The present exemplary embodiment is executedwhen the CONTINUOUS CALIBRATION button 1304 in an operations portalscreen 1301 illustrated in FIG. 13 is pressed to instruct execution of“continuous calibration” in which monochromatic calibration andmulti-color calibration are automatically executed in succession in thisorder.

The storage device 121 of the MFP 101 is able to store informationincluding a pair of the target value (A) and the target value (B)corresponding to each of a plurality of paper types, and time stampinformation indicating the date and time of registration of the pair ofthe target value (A) and the target value (B). The storage device 121 ofthe MFP 101 can further store information including the target value (C)corresponding to each of a plurality of paper types, and time stampinformation indicating the date and time of registration of the targetvalue (C) corresponding to the relevant paper type.

Further, for the 1D-LUT 218 and the 4D-LUT 217, the storage device 121is able to store time stamp information indicating the date and time ofLUT generation and paper information indicating paper used for LUTgeneration. The paper information includes at least the paper type.

FIG. 7 illustrates an example of the MONOCHROMATIC CALIBRATION executioninstruction screen 701.

The MONOCHROMATIC CALIBRATION execution instruction screen 701 includesat least a REGISTER CORRECTION PAPER button 702, a SELECT CORRECTIONPAPER button 703, and an EXECUTE button 704.

When the REGISTER CORRECTION PAPER button 702 is pressed, the screenchanges to the screen illustrated in FIG. 8. When the SELECT CORRECTIONPAPER button 703 is pressed, the screen changes to the screenillustrated in FIG. 9.

Upon reception of an execution start instruction by the press of theEXECUTE button 704, the CPU 103 executes monochromatic calibrationillustrated in FIG. 3 based on the target value (A) of the maximum valueand the target value (B) of the gradation characteristics correspondingto the paper selected when the relevant button is pressed.

FIG. 8 illustrates a MONOCHROMATIC CALIBRATION paper registration screen801 displayed when the REGISTER CORRECTION PAPER button 702 is pressed.Although FIG. 8 illustrates a case of three different registerable papertypes (correction paper 1 802, correction paper 2 803, and correctionpaper 3 804), registerable paper types are not limited thereto. One,two, or more number of paper types can be registered. The MONOCHROMATICCALIBRATION screen 801 enables storing the paper type (the correctionpaper 1, the correction paper 2, and the correction paper 3), the targetvalue (A), and the target value (B) in combination. More specifically,when plain paper A is registered as the correction paper 1, the targetvalue (A) and the target value (B) corresponding to plain paper A arestored in association with information indicating the relevant papertype (plain paper A). Likewise, when thick paper is registered as thecorrection paper 2, the target value (A) and the target value (B)corresponding to thick paper are stored in association with informationindicating the relevant paper type (thick paper).

Processing for associating a paper type with target values (orparameters for generating the target values) corresponding to therelevant paper type and then storing the relevant information in thisway is referred to as registration processing.

When the registration completion button 805 is pressed, the screenchanges to the MONOCHROMATIC CALIBRATION execution instruction screen701 illustrated in FIG. 7.

FIG. 9 illustrates a MONOCHROMATIC CALIBRATION paper selection screen901 displayed when the SELECT CORRECTION PAPER button 703 is pressed.Referring to FIG. 9, the paper information (paper type) of thecorrection paper registered in the MONOCHROMATIC CALIBRATION paperregistration screen 801 is displayed in display fields 902, 903, and904. The user is allowed to select a paper type to be used forsubsequent monochromatic calibration. When the selection complete button905 is pressed, the screen changes to the MONOCHROMATIC CALIBRATIONexecution instruction screen 701 illustrated in FIG. 7.

FIG. 10 illustrates an example of the MULTI-COLOR CALIBRATION executioninstruction screen 1001.

The MULTI-COLOR CALIBRATION execution instruction screen 1001 includesat least a REGISTER CORRECTION PAPER button 1002, a SELECT CORRECTIONPAPER button 1003, and an EXECUTE button 1004.

Upon reception of an execution start instruction by the depression ofthe EXECUTE button 1004, the CPU 103 executes multi-color calibrationillustrated in FIG. 4 based on the target value (C) corresponding to thepaper selected when the relevant button is pressed.

When the REGISTER CORRECTION PAPER button 1002 is pressed, the screenchanges to the screen illustrated in FIG. 11. When the SELECT CORRECTIONPAPER button 1003 is pressed, the screen changes to the screenillustrated in FIG. 12.

FIG. 11 illustrates a MULTI-COLOR CALIBRATION paper registration screen1101 displayed when the REGISTER CORRECTION PAPER button 1002 ispressed. Although FIG. 11 illustrates three different registerable papertypes (correction paper 1 1102, correction paper 2 1103, and correctionpaper 3 1104), registerable paper types are not limited thereto. One,two, or more number of paper types can be registered. The MULTI-COLORCALIBRATION screen 1101 enables storing the paper type (correction paper1, the correction paper 2, and the correction paper 3) and the targetvalue (C) in combination. More specifically, when plain paper A isregistered as the correction paper 1, the target value (C) correspondingto plain paper A is stored in association with information indicatingthe relevant paper type (plain paper A).

When the registration completion button 805 is pressed, the screenchanges to the MULTI-COLOR CALIBRATION execution instruction screen 1001illustrated in FIG. 10.

FIG. 12 illustrates a MULTI-COLOR CALIBRATION paper selection screen1201 displayed when the SELECT CORRECTION PAPER button 1003 is pressed.Referring to FIG. 12, the paper information (paper type) of thecorrection paper registered in the MULTI-COLOR CALIBRATION paperregistration screen 1101 is displayed in displayed fields 1202, 1203,and 1204. The user is allowed to select a paper type to be used forsubsequent multi-color calibration. When the selection complete button1205 is pressed, the screen changes to the MULTI-COLOR CALIBRATIONexecution instruction screen 1001 illustrated in FIG. 10.

In a first exemplary embodiment, the MFP 101 is used as an image formingapparatus, and paper to be used for continuous calibration is selectedwhen the user instructs execution of continuous calibration. Thefollowing describes operations for selecting paper.

FIG. 6 illustrates an example of the sheet feeding unit 116 of the MFP101. In the first exemplary embodiment, the MFP 101 is provided with afirst sheet feed stage 601, a second sheet feed stage 602, a third sheetfeed stage 603, a fourth sheet feed stage 604, and a fifth sheet feedstage 605 for storing paper. These sheet feed stages are able to storedifferent types of paper.

The CPU 103 inputs paper information indicating paper stored in eachsheet feed stage from the input unit 120, associates the first to thefifth sheet feed stages 601 to 605 with the paper information, andstores sheet feed stage information in the storage device 121. Although,in the present exemplary embodiment, the first to the fifth sheet feedstages as an example may be trays and manual feed slots, the form ofthese sheet feed stages is not limited thereto. The MFP 101 may beprovided with at least one sheet feed stage.

FIG. 14 is a flowchart illustrating operations according to the presentexemplary embodiment.

Each step of the flowchart is implemented when the CPU 103 loads acontrol program (not illustrated) stored in the storage device 121 intoa RAM (not illustrated) and then executes it.

The processing illustrated in FIG. 14 is activated after completion ofpaper registration in each of the flowcharts illustrated in FIGS. 8 and11.

When the CONTINUOUS CALIBRATION button 1304 is pressed in the operationsportal screen 1301, then in step S1401, the CPU 103 reads from thestorage device 121 paper information indicating paper types registeredto be used at the time of execution of monochromatic calibration.

In step S1402, the CPU 103 reads from the storage device 121 paperinformation indicating paper types registered to be used at the time ofexecution of multi-color calibration.

The CPU 103 compares the registered paper for monochromatic calibrationread in step S1401 with the registered paper for multi-color calibrationread in step S1402. In step S1403, out of the paper types registered aspaper to be used for respective calibrations, the CPU 103 extracts anddetermines paper types registered in common for respectivelycalibrations. FIG. 15 illustrates an example of paper types registeredto be used at the time of execution of monochromatic calibration andpaper types registered to be used at the time of execution ofmulti-color calibration. Plain paper A, thick paper, and coated paperare assumed to have been registered for monochromatic calibration. Plainpaper A, plain paper B, and coated paper are assumed to have beenregistered for multi-color calibration. In this case, plain paper A andcoated paper are extracted and determined as common paper types.Hereinafter, these extracted paper types are referred to as “commonpaper types”.

In step S1404, the CPU 103 reads sheet feed stage information from thestorage device 121, and compares the relevant information with thecommon paper types determined in step S1403.

In step S1405, as a result of the comparison in step S1404, the CPU 103determine whether any sheet stage stores paper belonging to the commonpaper types.

When a sheet feed stage is determined to store paper belonging to thecommon paper types determined in step S1405 (YES in step S1405), then instep S1406, the CPU 103 displays on the display unit 118 the sheet feedstage storing paper belonging to the common paper types, as illustratedin FIG. 16.

FIG. 16 illustrates an example of a sheet feed stage selection(CONTINUOUS CALIBRATION) screen 1601 displayed when the CONTINUOUSCALIBRATION button 1304 is pressed. The CONTINUOUS CALIBRATION screen1601 displays paper information indicating paper stored in the first tothe fifth sheet feed stages, as well as sheet feed stages storing paperbelonging to the common paper types determined in step S1405. Sheet feedstages storing paper types registered as paper to be used only for onecalibration are grayed out. This means that paper stored in the sheetfeed stages grayed out cannot be used at the time of execution ofcontinuous calibration. Specifically, in the present exemplaryembodiment, only plain paper A in the sheet feed stage 1 and coatedpaper in the sheet feed stage 3 can use used at the time of execution ofcontinuous calibration. Although, in the present exemplary embodiment,sheet feed stages storing paper unusable for continuous calibration aregrayed out, the processing is not limited thereto.

For example, the screen may display only sheet feed stages storing paperusable at the time of execution of continuous calibration, asillustrated in FIG. 17, as long as the relevant usable sheet feed stagesare distinguished from other (unusable) sheet feed stages. In stepS1407, the CPU 103 determines whether paper usable at the time ofexecution of continuous calibration, i.e., whether the sheet feed stage1 or the sheet feed stage 3, has been selected and then the continuouscalibration execution (EXECUTE) button 1602 has been pressed. The CPU103 waits until the continuous calibration execution (EXECUTE) button1602 is pressed. When the continuous calibration execution (EXECUTE)button 1602 is determined to have been pressed (YES in step S1407), theprocessing exits this flowchart and proceeds to execution of continuouscalibration.

When none of the sheet feed stages is determined to store paperbelonging to the common paper types (NO in step S1405), then in stepS1408, the CPU disables the continuous calibration execution (EXECUTE)button 1602 illustrated in FIG. 16. In step S1409, the CPU 103 monitorswhether paper has been replaced in any one of the five sheet feedstages.

In step S1409, the sheet feed stage selection (CONTINUOUS CALIBRATION)screen 1601 or 1701 illustrated in FIG. 16 or 17, respectively, mayprompt the user to store paper belonging to any one of the paper typesdetermined in step S1403 in one of the sheet feed stages. When paper isdetermined to have been replaced in any one of the five sheet feedstages (YES in step S1409), then in step S1410, the CPU 103 determineswhether the replaced paper is paper belonging to the common paper types.The CPU 103 detects replacement of paper by using a sheet feed stageopen/close sensor (not illustrated) for detecting opening and closing ofeach sheet feed stage. The CPU 103 monitors a signal from the sheet feedstage open/close sensor. When the sheet feed stage open/close sensoroutputs a sheet feed stage open signal and, immediately after thissignal, outputs a sheet feed stage close signal, the CPU 103 determinesthat paper has been replaced in the relevant sheet feed stage.Subsequently, the user inputs paper information indicating paper storedin each sheet feed stage from the input unit 120, and compares the paperinformation with the previously input paper information. If there is adifference between the two pieces of paper information, the CPU 103determines that paper has been replaced in the relevant sheet feedstage. Based on the paper information, the CPU 103 is able to determinewhether the replaced paper is paper belonging to the common paper types.

When the paper is determined to be paper belonging to the common papertypes (YES in step S1410), the processing proceeds to step S1406. Whenthe paper is determined not to be paper belonging to the common papertypes (NO in step S1410), the processing returns to step S1409, and theCPU 103 waits for replacement of paper.

A CANCEL button (not illustrated) is constantly displayed on the displayunit 118. When the CANCEL button is pressed, the CPU 103 forcibly stopsall the above-described operations, and displays a screen equivalent tothe initial screen of the apparatus.

As described above, according to the present exemplary embodiment, inthe case of continuous execution of a plurality of calibrations fordifferent correction targets, the user is allowed to select a paper typeof paper to be used for calibrations or select a sheet feed stagestoring paper belonging to the selected paper type through one piece ofprocessing. This facilitates operations for selecting a sheet feed stageat the time of execution of continuous calibration. Further, in the caseof continuous execution of a plurality of calibrations for differentcorrection targets, the apparatus is able to receive a calibrationexecution instruction from the user with reduced processing. Thisenables reducing user's workloads to reduce user's intervention wheninstructing calibration execution.

In the case of continuous execution of a plurality of calibrations fordifferent correction targets, such as monochromatic calibration andmulti-color calibration, it becomes easier to conform a paper type ofpaper to be used at the time of execution of monochromatic calibrationto a paper type of paper to be used at the time of execution ofmulti-color calibration. This eliminates the need of registering aplurality of target values for multi-color calibration.

The following describes a second exemplary embodiment based on anotherform of operations for selecting paper to be used at the time ofexecution of continuous calibration when the CONTINUOUS CALIBRATIONbutton 1304 is pressed in the operations portal screen 1301.

FIG. 18 is a flowchart illustrating operations according to the presentexemplary embodiment.

Each step of the flowchart is implemented when the CPU 103 loads acontrol program (not illustrated) stored in the storage device 121 intoa RAM (not illustrated) and then executes it.

When the CONTINUOUS CALIBRATION button 1304 is pressed in the operationsportal screen 1301, then in step S1801, the CPU 103 reads from thestorage device 121 paper information indicating paper types registeredto be used at the time of execution of monochromatic calibration.

In step S1802, the CPU 103 reads from the storage device 121 paperinformation indicating paper types registered to be used at the time ofexecution of multi-color calibration.

In step S1803, the CPU 103 reads sheet feed stage information from thestorage device 121, and then, as illustrated in step S1403, determinespaper types registered to be used in common for both calibrations out ofpaper types registered as paper to be used at the time of execution ofeach calibration.

In step S1804, the CPU 103 displays a sheet feed stage selection(CONTINUOUS CALIBRATION) screen 1901 indicating the status of each sheetfeed stage of the MFP 101, as illustrated in FIG. 19.

FIG. 19 illustrates an example of the sheet feed stage selection(CONTINUOUS CALIBRATION) screen 1901 displayed when the CONTINUOUSCALIBRATION button 1304 is pressed. The CONTINUOUS CALIBRATION screen1901 displays paper information indicating paper stored in the first tothe fifth sheet feed stages, as well as information about paper storedin each sheet feed stage obtained in the determination processing instep S1803, i.e., whether paper is usable at the time of execution ofmonochromatic calibration and at the time of execution of multi-colorcalibration. Referring to FIG. 19, a circle (o) indicates that therelevant paper is usable for each calibration, and a cross (x) indicatesthat the relevant paper is not usable therefor.

For example, when the registered paper status is as illustrated in FIG.15, the sheet feed stage selection (CONTINUOUS CALIBRATION) screen 1901displays information as illustrated in FIG. 19.

In each of the x display fields, a monochromatic calibration paperregistration (REGISTER) button 1902 or a multi-color calibration paperregistration (REGISTER) button 1903 is displayed.

When the sheet feed stage 1 or the sheet feed stage 3 is selected andthen the CONTINUOUS CALIBRATION button 1304 is pressed in the sheet feedstage selection (CONTINUOUS CALIBRATION) screen 1901 (YES in stepS1805), the processing exits this flowchart and proceeds to execution ofcontinuous calibration.

When neither the sheet feed stage 1 nor the sheet feed stage 3 isselected (NO in step S1805), then in step S1806, the CPU 103 determineswhether the monochromatic calibration paper registration (REGISTER)button 1902 has been pressed. When the monochromatic calibration paperregistration (REGISTER) button 1902 is determined to have been pressed(YES in step S1806), then in step S1808, the screen changes to theMONOCHROMATIC CALIBRATION paper registration screen 801, and terminatesthe continuous calibration operation.

When the screen changes to the MONOCHROMATIC CALIBRATION paperregistration screen 801, the screen may return to the sheet feed stageselection (CONTINUOUS CALIBRATION) screen 1901 illustrated in FIG. 19 toregister paper to be used at the time of execution of monochromaticcalibration and then execute continuous calibration.

When the monochromatic calibration paper registration (REGISTER) button1902 is determined not to be pressed (NO in step S1806), then in stepS1807, the CPU 103 determines whether the multi-color calibration paperregistration (REGISTER) button 1903 has been pressed. When themulti-color calibration paper registration (REGISTER) button 1903 isdetermined to have been pressed (YES in step S1807), then in step S1809,the screen changes to the MULTI-COLOR CALIBRATION paper registrationscreen 1101, and terminates the continuous calibration operation. Whenthe screen changes to the MULTI-COLOR CALIBRATION paper registrationscreen 1101, the screen may return to the sheet feed stage selection(CONTINUOUS CALIBRATION) screen 1901 illustrated in FIG. 19 to registerpaper to be used at the time of execution of multi-color calibration andthen execute continuous calibration.

When the multi-color calibration paper registration (REGISTER) button1903 is determined not to be pressed (NO in step S1807), the processingreturns to step S1805.

Configuring the present exemplary embodiment as described above enablesachieving the effect of the first exemplary embodiment, and enablesclearly indicating information about sheet feed stages unusable forcontinuous calibration and which calibration each of the relevant sheetfeed stages is unusable for. Therefore, when paper belonging to a targetpaper type is unusable at the time of execution of continuouscalibration, the CPU 103 is able to change to each calibration paperregistration screen with reduced user operations, and register a desiredpaper type. Thus, it becomes possible to provide the user with auser-friendly operation screen.

FIG. 20 illustrates a sheet feed stage selection (CONTINUOUSCALIBRATION) screen 2001 displayed in step S1406 according to a thirdexemplary embodiment. The CONTINUOUS CALIBRATION screen 2001 displaysonly sheet feed stages storing paper usable for continuous calibration,and a DETAILED SETTING button 2002.

When the DETAILED SETTING button 2002 is pressed, the screen changes tothe sheet feed stage selection (CONTINUOUS CALIBRATION) screen 1901.When the screen changes to the sheet feed stage selection (CONTINUOUSCALIBRATION) screen 1901, the CPU 103 executes again operations in stepS1804 and subsequent steps.

As described above, configuring the present exemplary embodiment asdescribed above enables executing continuous calibration with easyoperations, providing detailed information only when necessary, anddisplay each calibration paper registration screen with reducedoperations.

The present invention is also achieved by performing the followingprocessing. Specifically, software (a program) for achieving thefunctions of the above-described exemplary embodiments is supplied to asystem or an apparatus via a network or various storage media, and acomputer (or a CPU or a microprocessor unit (MPU)) of the system or theapparatus reads the program and executes it.

Although the exemplary embodiments have specifically been describedbased on an electrophotographic apparatus, the exemplary embodiments arealso applicable to an ink-jet printer and a thermal printer. The spiritor scope of the present invention is not limited to printer types.Although the exemplary embodiments have specifically been describedbased on toner in electrophotographic printing as a recording agent, therecording agent is not limited to toner, and may be ink or otherrecording agents. The spirit or scope of the present invention is notlimited to recording agent types.

Embodiments of the present invention can also be realized by a computerof a system or apparatus that reads out and executes computer executableinstructions recorded on a storage medium (e.g., non-transitorycomputer-readable storage medium) to perform the functions of one ormore of the above-described embodiment(s) of the present invention, andby a method performed by the computer of the system or apparatus by, forexample, reading out and executing the computer executable instructionsfrom the storage medium to perform the functions of one or more of theabove-described embodiment(s). The computer may comprise one or more ofa central processing unit (CPU), micro processing unit (MPU), or othercircuitry, and may include a network of separate computers or separatecomputer processors. The computer executable instructions may beprovided to the computer, for example, from a network or the storagemedium. The storage medium may include, for example, one or more of ahard disk, a random-access memory (RAM), a read only memory (ROM), astorage of distributed computing systems, an optical disk (such as acompact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™,a flash memory device, a memory card, and the like.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

What is claimed is:
 1. An image processing apparatus comprising: animage forming unit configured to form a color image using recordingmaterials; a calibration control unit configured to control execution ofa single color calibration, the single color calibration being executedby measurement of single color patch image that is formed using only asingle color recording material by the image forming unit andgenerating, using a measurement result, single color calibration data,and execution of a multi-color calibration, the multi-color calibrationbeing executed by measurement of multi-color patch image that is formedusing at least two types of color recording materials by the imageforming unit and generating, using a measurement result, multi-colorcalibration data; a control unit configured to control such that in acase where the control unit is instructed that the single colorcalibration and the multi-color calibration are executed, a paper typeof paper used at a time of execution of the multi-color calibrationmatches a paper type of paper used at a time of execution of the singlecolor calibration.
 2. The image processing apparatus according to claim1, wherein the single color calibration data is generated by using ameasurement result of a pattern image including a plurality of singlecolor patch images, each of the plurality of patch images being formedusing only a single color recording material by the image forming unit.3. The image processing apparatus according to claim 2, wherein theplurality of single color patch images are different in density.
 4. Theimage processing apparatus according to claim 3, wherein the pluralityof single color patch images each are formed using color recordingmaterials of different colors.
 5. The image processing apparatusaccording to claim 1, wherein the multi-color calibration data isgenerated by using a measurement result of a pattern image including aplurality of multi-color patch images, each patch image being formedusing at least two types of recording materials by the image formingunit.
 6. The image processing apparatus according to claim 1, whereinthe paper type indicates information about size and basis weight of apaper.
 7. The image processing apparatus according to claim 1, whereinthe control unit controls paper used at a time of execution of themulti-color calibration and paper used at a time of execution of thesingle color calibration to be fed from a same cassette.
 8. The imageprocessing apparatus according to claim 1, wherein the control unitperforms control to prohibit using a paper of which type is differentform a type of paper used at a time of execution of the single colorcalibration for execution of the multi-color calibration.
 9. An imageprocessing method comprising controlling execution of a single colorcalibration, the single color calibration being executed by measurementof single color patch image that is formed using only a single colorrecording material by an image forming unit using and generating, usinga measurement result, single color calibration data, controllingexecution of a multi-color calibration, the multi-color calibrationbeing executed by measurement of multi-color patch image that is formedusing at least two types of color recording materials by the imageforming unit and generating, using a measurement result, multi-colorcalibration data; controlling such that in a case where the single colorcalibration and the multi-color calibration are instructed to beexecuted, a paper type of paper used at a time of execution of themulti-color calibration matches a paper type of paper used at a time ofexecution of the single color calibration.
 10. A non-transitorycomputer-readable storage medium storing a program that causes acomputer to execute a method comprising: controlling execution of asingle color calibration, the single color calibration being executed bymeasurement of single color patch image that is formed using only asingle color recording material by an image forming unit using andgenerating, using a measurement result, single color calibration data,controlling execution of a multi-color calibration, the multi-colorcalibration being executed by measurement of multi-color patch imagethat is formed using at least two types of color recording materials bythe image forming unit and generating, using a measurement result,multi-color calibration data; controlling such that in a case where thesingle color calibration and the multi-color calibration are instructedto be executed, a paper type of paper used at a time of execution of themulti-color calibration matches a paper type of paper used at a time ofexecution of the single color calibration.